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authorIestyn C. Elfick <isedev@gmail.com>2013-03-20 14:02:31 -0500
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-04-05 10:16:36 -0700
commit1c9c0901afba44cf1353505b72e146e7f87a54b6 (patch)
tree3cf729f26842e7a84fd521a89f63d32d5f10181b
parentb76c1eabd474cd44937fc60a26be2b926a366e55 (diff)
downloadlinux-linaro-stable-1c9c0901afba44cf1353505b72e146e7f87a54b6.tar.gz
b43: A fix for DMA transmission sequence errors
commit b251412db99ccd4495ce372fec7daee27bf06923 upstream. Intermittently, b43 will report "Out of order TX status report on DMA ring". When this happens, the driver must be reset before communication can resume. The cause of the problem is believed to be an error in the closed-source firmware; however, all versions of the firmware are affected. This change uses the observation that the expected status is always 2 less than the observed value, and supplies a fake status report to skip one header/data pair. Not all devices suffer from this problem, but it can occur several times per second under heavy load. As each occurence kills the unmodified driver, this patch makes if possible for the affected devices to function. The patch logs only the first instance of the reset operation to prevent spamming the logs. Tested-by: Chris Vine <chris@cvine.freeserve.co.uk> Signed-off-by: Larry Finger <Larry.Finger@lwfinger.net> Signed-off-by: John W. Linville <linville@tuxdriver.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/net/wireless/b43/dma.c65
1 files changed, 53 insertions, 12 deletions
diff --git a/drivers/net/wireless/b43/dma.c b/drivers/net/wireless/b43/dma.c
index 47d44bcff37d..5deeb14b8232 100644
--- a/drivers/net/wireless/b43/dma.c
+++ b/drivers/net/wireless/b43/dma.c
@@ -1390,8 +1390,12 @@ void b43_dma_handle_txstatus(struct b43_wldev *dev,
struct b43_dmaring *ring;
struct b43_dmadesc_generic *desc;
struct b43_dmadesc_meta *meta;
+ static const struct b43_txstatus fake; /* filled with 0 */
+ const struct b43_txstatus *txstat;
int slot, firstused;
bool frame_succeed;
+ int skip;
+ static u8 err_out1, err_out2;
ring = parse_cookie(dev, status->cookie, &slot);
if (unlikely(!ring))
@@ -1404,13 +1408,36 @@ void b43_dma_handle_txstatus(struct b43_wldev *dev,
firstused = ring->current_slot - ring->used_slots + 1;
if (firstused < 0)
firstused = ring->nr_slots + firstused;
+
+ skip = 0;
if (unlikely(slot != firstused)) {
/* This possibly is a firmware bug and will result in
- * malfunction, memory leaks and/or stall of DMA functionality. */
- b43dbg(dev->wl, "Out of order TX status report on DMA ring %d. "
- "Expected %d, but got %d\n",
- ring->index, firstused, slot);
- return;
+ * malfunction, memory leaks and/or stall of DMA functionality.
+ */
+ if (slot == next_slot(ring, next_slot(ring, firstused))) {
+ /* If a single header/data pair was missed, skip over
+ * the first two slots in an attempt to recover.
+ */
+ slot = firstused;
+ skip = 2;
+ if (!err_out1) {
+ /* Report the error once. */
+ b43dbg(dev->wl,
+ "Skip on DMA ring %d slot %d.\n",
+ ring->index, slot);
+ err_out1 = 1;
+ }
+ } else {
+ /* More than a single header/data pair were missed.
+ * Report this error once.
+ */
+ if (!err_out2)
+ b43dbg(dev->wl,
+ "Out of order TX status report on DMA ring %d. Expected %d, but got %d\n",
+ ring->index, firstused, slot);
+ err_out2 = 1;
+ return;
+ }
}
ops = ring->ops;
@@ -1424,11 +1451,13 @@ void b43_dma_handle_txstatus(struct b43_wldev *dev,
slot, firstused, ring->index);
break;
}
+
if (meta->skb) {
struct b43_private_tx_info *priv_info =
- b43_get_priv_tx_info(IEEE80211_SKB_CB(meta->skb));
+ b43_get_priv_tx_info(IEEE80211_SKB_CB(meta->skb));
- unmap_descbuffer(ring, meta->dmaaddr, meta->skb->len, 1);
+ unmap_descbuffer(ring, meta->dmaaddr,
+ meta->skb->len, 1);
kfree(priv_info->bouncebuffer);
priv_info->bouncebuffer = NULL;
} else {
@@ -1440,8 +1469,9 @@ void b43_dma_handle_txstatus(struct b43_wldev *dev,
struct ieee80211_tx_info *info;
if (unlikely(!meta->skb)) {
- /* This is a scatter-gather fragment of a frame, so
- * the skb pointer must not be NULL. */
+ /* This is a scatter-gather fragment of a frame,
+ * so the skb pointer must not be NULL.
+ */
b43dbg(dev->wl, "TX status unexpected NULL skb "
"at slot %d (first=%d) on ring %d\n",
slot, firstused, ring->index);
@@ -1452,9 +1482,18 @@ void b43_dma_handle_txstatus(struct b43_wldev *dev,
/*
* Call back to inform the ieee80211 subsystem about
- * the status of the transmission.
+ * the status of the transmission. When skipping over
+ * a missed TX status report, use a status structure
+ * filled with zeros to indicate that the frame was not
+ * sent (frame_count 0) and not acknowledged
*/
- frame_succeed = b43_fill_txstatus_report(dev, info, status);
+ if (unlikely(skip))
+ txstat = &fake;
+ else
+ txstat = status;
+
+ frame_succeed = b43_fill_txstatus_report(dev, info,
+ txstat);
#ifdef CONFIG_B43_DEBUG
if (frame_succeed)
ring->nr_succeed_tx_packets++;
@@ -1482,12 +1521,14 @@ void b43_dma_handle_txstatus(struct b43_wldev *dev,
/* Everything unmapped and free'd. So it's not used anymore. */
ring->used_slots--;
- if (meta->is_last_fragment) {
+ if (meta->is_last_fragment && !skip) {
/* This is the last scatter-gather
* fragment of the frame. We are done. */
break;
}
slot = next_slot(ring, slot);
+ if (skip > 0)
+ --skip;
}
if (ring->stopped) {
B43_WARN_ON(free_slots(ring) < TX_SLOTS_PER_FRAME);